Integrated circuits (IC) are used in a variety of applications. Generally speaking, programmable logic devices (PLDs) such as field-programmable gate arrays (FPGAs) and application-specific integrated circuits (ASICs) are devices that include generic structures and logic blocks that can be configured to perform different functions. Some of these logic blocks include logic circuitry, registers, input/output (I/O) blocks, transceiver channels, etc. These circuitry elements are programmable to perform any of a variety of tasks and functions. For instance, PLDs with embedded high-speed serial transceiver blocks can be used to implement a Gigabit Passive Optical Network (GPON) protocol.
Generally speaking, a passive optical network (PON) is a network architecture that brings fiber cabling and signals to a user node, e.g., a home, using a point-to-multipoint scheme that enables a single optical fiber to serve multiple premises. The GPON protocol is a specific PON standard that provides a higher bandwidth, higher efficiency and a generally higher quality of service for high-speed communication traffic. However, certain problems that may arise in a GPON implementation need to be addressed. Some of the challenges when implementing a GPON protocol include, among others, long dead time, multiple phase jumps and short preamble requirements.
Typically, a PON network includes an optical line terminal (OLT) which is normally located at the service provider's end and multiple optical network units (ONUs) near all the end users. A splitter or a combiner is usually placed in between the OLT and the ONUs. Downstream signals from the OLT is split and sent to different ONUs and upstream signals from the users are combined and sent to the OLT. Generally speaking, each user has an assigned slot that allows the OLT to receive packets from each different user. High-speed signals from each different user usually have different phases and hence need to be sampled quickly and accurately.
Therefore, it is desirable to have a sampling technique that is able to sample all these high-speed signals accurately. It is also desirable to have a sampling technique that can handle long dead time and multiple phase jump angles in data streams.